USE OF HANDS BY MONKEYS 143 



class since a slight change in the totals might throw him into 

 either of the above classes. Table II shows that monkey i 

 after the operation showed a decided preference for the right 

 hand, and that in the few observations with monkey 8 a sim- 

 ilar tendency was present. It is possible that the effects of 

 the operation, although on the occipital lobe, may have had 

 an influence on the animal's use of the hands, and for purposes 

 of a general comparison these results may properly be omitted. 

 These animals did, in fact, show inaccuracies in movement fol- 

 lowing the operation, but I was not able to determine any 

 difference between the tw T o sides of the body. 3 



In 114 of the tests w r ith monkey 1, the animal took both 

 pieces of bread, and in 182 tests only the sweet bread. When 

 only the sweet bread was taken, the right hand was used 70 

 times, the left 112; when both pieces of bread were taken the 

 right hand was used 52 times for both pieces (104 times), the 

 left hand 28 times for both pieces (56 times), and in 34 tests 

 both hands were used, one piece being taken in each hand. In 

 all tests in which both pieces of bread were taken we may count 

 that one piece was to the right and the other to the left of the 

 animal ; in the tests in which only one piece was taken the food 

 taken was 93 times on the right and 89 times on the left. No 

 account was taken of the positions of the pieces of food which 

 were taken first when the tw r o pieces were picked up, so that 

 any correlation between the location of the food pieces is im- 

 possible for the total series. Only the occasions on which the 

 animal picked up one piece can be used for this, and from the 

 above figures (93 times on the right and 89 on the left) we find 

 that the right hand was used for the picking up of the food 37 

 times on the right and 33 times on the left, and the left hand 

 was used for taking the food which was 56 times on the right 

 and 56 times on the left. In the case of this animal, therefore, 

 the position of the food had no perceptible influence on the 

 use of the individual hand. 



In 185 of the tests with monkey 8, the animal took only one 

 of the pieces of food which were before him; in 75 tests both 

 pieces were taken. In the tests in which one piece of food was 

 taken the right hand was used 32 times, the left 153 times; in 

 the tests in which both pieces were taken the right hand was 



3 For details see my monograph, cited above, pp. 44-52; 95-97. 



